First lady Michelle Obama doesn't want her two young daughters to have a big presence on Facebook yet, she told ABC News' Barbara Walters in an interview.

"I still am not a big believer in Facebook for young people…particularly for them, because they're in the public eye," Mrs. Obama said. "Some of its stuff they don't need to see and be a part of… So we try to protect them from too much of the public voice."

Barbara Walters' exclusive interview with President Obama and first lady Michelle Obama airs on a special edition of "20/20," "Walters at the White House," on Friday, Nov. 29, at 10 p.m. ET.

Sasha, 12, isn't old enough to be on the social networking site yet, Obama said, and 15-year-old Malia's access to social media is still limited.

For the first time since Chelsea Clinton, the White House now has teenaged (and pre-teen) residents. But it comes at a time of unprecedented public access to high-profile figures through Facebook, Twitter, Instagram and other social networks.

Still, the Obamas say they encourage their daughters to grow personally while their father is commander-in-chief.

Malia Obama, a sophomore in high school, is allowed to date - though her parents won't say whether she is seeing anyone now - and they frequently have sleepovers and pajama parties on the White House's third floor.

"You know, we think about not just her life here, but her life after. Because she's gotta be an independent, strong, smart, capable woman in the world," Michelle Obama says of Malia. "So she has to get her training now."

"She can't wait until this light has dimmed to start becoming a person," she added.